Subject: [homenet] some IS-IS questions

From: "STARK, BARBARA H" <[email-masked]>
Date: Mon, 27 Jul 2015 20:50:06 +0000

Given some of the discussion last week, I found that I had some questions about what is or isn't already defined somewhere within the set of IS-IS specs *and* is already implemented in a load suitable for a homenet router. I've read the Babel specs, so I have a good idea of what's in Babel. Plus there was that really good Babel presentation Thursday night. But I'm having real trouble finding the right IS-IS specs to answer my questions.

There was a claim that IS-IS provides "diagnostics". 
What sort of diagnostics? Is this a reference to topology discovery? Does topology discovery rely on device participation in IS-IS, or can devices that do not participate in IS-IS be discovered? Can bridged devices be discovered? If yes, can they be discovered even if they don't do IS-IS? If yes, how does that work?
Can physical layer topology be discovered?
What additional diagnostics outside of topology discovery does IS-IS support?

I was told that IS-IS can help avoid loops caused by bridged interfaces as well as routed interfaces? Is this correct? If yes, does it rely on participation of bridges in IS-IS, or can it be done with only participation by routers?

I was told that with IS-IS a "service provider" router could somehow automatically take control of QoS and routing policy in the network, and dictate policy to other routers (assuming the other routers even have a QoS policy). Is this true? How does this work, especially if there are multiple "service provider" routers? Would this be in the IS-IS version suitable for homenet?

I was told that if IS-IS is selected, hosts will be able to do resource reservation across the homenet. Resource reservation has yet to be implemented in unmanaged home network devices, though many standards have been written. In general, the complexity of supporting resource reservation schemes has never been worth the cost. Is this something that will suddenly work as a result of IS-IS implementation in routers? Is it in the IS-IS subset proposed for homenet? What does it require in the hosts?
Barbara